Marker lights of the type herein involved are used primarily by military forces in combat areas to mark the boundaries of safe aircraft landing areas or drop zones, to mark roadways or obstructions and for a variety of other signalling purposes where it is desirable to provide some visible indication of either safe or hazardous conditions, without requiring manned attendance. Such uses are usually of a temporary or emergency nature and conditions often require that the markers be easily transported then rapidly deployed with a minimum amount of attention to their secure and precise placement. Often, the marker lights are distributed by dropping the lights at intervals from a moving vehicle. Such a method requires that the marker lights be capable of erecting themselves to an operative position at or near their intended location and that they remain reasonably well fixed on site.
Marker lights designed specifically for such purposes are disclosed in U.S. Pat. No. 2,806,131, issued Sep. 10, 1957 and U.S. Pat. No. 4,563,668, issued Jan. 7, 1986 and in U.S. Military Specification MIL-L-52543C, dated Oct. 7, 1976, available from Commander, US Army Mobility Equipment Research and Development Command, ATTN: DRXFB-DS, Fort Belvoir, Va. 22060.
The marker lights disclosed in the above references comprise a cylindrical housing closed at the bottom end. The lower portion of the housing encloses a dry cell battery above which is mounted a three position switch and a printed circuit board supporting a lamp flasher circuit. The switch operating lever extends to the exterior of the housing and is covered by a rubber boot. The printed circuit board is covered by a dome-like light deflector extending completely across the housing and having a white or reflective finish with a lamp socket and lamp mounted centrally thereon. The lamp and light deflector dome are covered by a transparent protective dome which has an outwardly projecting flange at the open end in abutment with the upper edge of the cylindrical housing. The protective dome and the underlying deflector dome are secured in position closing the upper end of the cylindrical housing by an internally threaded ring that engages mating threads formed around the outer upper edge of the cylindrical housing. The ring has an inwardly directed flange at its upper edge which captures the flange of the protective dome, along with a sealing gasket, and draws the dome and light deflector into a tightly seated contact with the upper rim of the housing.
The lower, major portion of the light housing is inserted through the neck of a ballast bag, extending into the interior of the bag. Prior to assembly of &.he light housing to the ballast bag, the bag is substantially filled with any suitable and available ballast material, such as sand, stones, soil or ice. The bag is then closed by inserting the light housing through the bag neck and tightly clamping the edge of the bag neck against the light housing by means of a hose clamp or similar device. In certain marker lights of the prior art, the ballast bag includes, in addition to the opening through which the light assembly is inserted, one or more openings fitted with flap closures to permit filling the bag with ballast without disturbing the assemblage of the light housing to the ballast bag.
Prior marker lights of the type described are prone to certain failures and disadvantages. The primary cause of failure is damage to the light assembly housing and various parts of the light assembly resulting from impact cf the marker light with the ground when the light is dropped from a moving vehicle. Disadvantages of the prior marker lights include: difficulty in installing the light assembly into the filled ballast bag; impact damage to the light housing when the ballast comprises hard, sharp material, such as rocks; difficulty in filling the bag completely with ballast material because of the inaccessibility of areas of the bag in the vicinity of the light housing; loss in stability because of the reduced capacity of the bag for ballast material, due to the presence of the light housing; poor low temperature performance when the light housing is frozen into cold ballast material, such as ice; difficulty in adjusting the light dome for directional control when a partially blacked-out light dome is used and difficulty in changing the light color when lights of various colors are used. Other shortcomings of prior marker lights will become evident hereinafter.
It is an object of the invention to provide a marker light of the type described having improved immunity to damage resulting from the shock of deployment.
Another object of this invention is to reduce the maintenance time on the marker light. The switch contact is frequently subject to premature failure due to environmental factors such as hot humid climates and other factors such as the destructive vapors emitted by deteriorating batteries. Therefore, improved and rapid maintenance is achieved when the switch contact is a component of the cover or circuit so that it is quickly replaced as the appropriate one of these components is replaced.
Another object of this invention is to provide a more compact marker light.
It is a further object of this invention to provide a marker light that functions with less components.
It is another object of this invention to provide a marker light that can have its circuit and switch contact simultaneously replaced during maintenance of one of these components without the prior necessity of disconnecting the switch from the housing.
It is another object of the invention to provide a marker light having a ballasted supporting base in which the light assembly is isolated from direct contact with the ballast material thereby reducing the likelihood of damage to the light assembly by impact of the ballast material against the light assembly and reducing the possibility of deterioration of the light assembly by moisture seepage from the ballast material into the light assembly, should the light assembly housing be fractured during deployment, and improving cold weather performance by eliminating the possibility of the battery case being frozen into the ballast.
It is another object of the invention to provide a marker light having an optional supporting base in the form a bag having a reclosable opening to permit filling the bag with available ballast material in which the interior of the bag is not obstructed by the housing of the marker light thereby increasing the capacity of the bag for ballast material, improving the stability of the marker light and permitting the bag to be filled completely through a single opening.
It is another object of the invention to provide a ballasted marker light which is rainproof without the use of rubber seals, and in which the light circuit connections and switch are formed by a printed circuit board, eliminating jumper wires and a discrete switch and in which the light circuit is opened when the cover is removed from the battery housing, thus precluding accidental or inadvertent illumination of the lamp when the lamp housing is partially disassembled.
It is a further object of the invention to provide a marker light in which the lamp bulb can be easily replaced, the color of the light can be easily changed and the directivity of the light can be easily altered.
It is still another object of the invention to provide a marker light of simplified construction and reduced cost of manufacture.
Other objects and advantages of the invention will become apparent as an understanding thereof is gained from the following complete description and the accompanying drawings. Brief Description of the Invention
Briefly, the marker light of the present invention comprises a marker light assembly having a cylindrical base portion closed at the bottom end and open at the top end which contains a battery compartment and storage space for spare lamp bulbs and bulb covers. The top end of the base portion is provided with three upwardly extending clamp arms spaced evenly about and spaced outward from the top rim of the base. A segmented flange extends outward from the top rim of the base near the lower ends of the clamp arms. The top end of the base is closed by a convex cover having a downwardly extending cylindrical rim with an outwardly projecting flange at the lower edge. The rim of the cover overlaps the top upper edge of the base.
A printed circuit board is mounted on the under side of the cover. The board includes a downwardly facing circuit pattern having contacts for engaging the battery terminals to connect the batteries either directly to the lamp for continuous illumination of the marker light or to an interrupter circuit through which the lamp receives intermittent power for flashing illumination of the marker light or for open circuiting the lamp. Thus, rotation of the cover with respect to the base orients the circuit board in three different azimuthal positions to perform the function of a three position switch having "on", "off" and "flash" positions. The cover is indexed to the base for proper orientation of the circuit board by an actuating arm which projects downward from the outer rim of the cover through a slotted flange extending outward from the upper end of the base.
A lamp socket, mounted on the upper surface of the board, projects through the center of the cover to receive a lamp. Components of the interrupter circuit are also mounted on the upper surface of the board. The lamp is optionally covered by a small translucent inner dome which may be colored with any of the conventional signal colors, such as red, green or amber.
The cover and inner dome are enclosed by a large, transparent outer dome which may be partially covered by an opaque finish so that the light will be visible only from a particular direction of approach. The lower rim of the outer dome is dimensioned to fit snugly over the cylindrical rim of the cover and is provided with an outwardly projecting flange which overlies and abuts against the flange of the cover. The outer dome is installed over the cover and the outer dome and cover are pressed down over the upper rim of the base until the flange of the outer dome is gripped by the clamp arms of the base. A secure assemblage of the cover and outer dome to the base is thus formed in which both the cover and the outer dome are relatively easily rotatable with respect to the base. The edge of the outer dome overlapping the upper rim of the base forms a rainproof seal without the use of a rubber gasket or a switch protective boot.
The marker light assembly can be used alone but is usually secured to the upper outer surface of a ballast bag, preferably by a pair of spaced rivets or removable nuts and screws passed through the bottom of the base of the light assembly and through the upper surface of the ballast bag. The bag may be suitably formed like a pillow case with an opening along one edge for inserting the ballast material, which may be closed by a zipper or snap fasteners or other suitable means. Tie down loops may also be attached to the corners of the bag for fixing the marker light in place by means of stakes or other suitable anchoring devices.